Memory device for storing data and reading data

1. A memory device comprising: a medium including a plurality of tracks, each of which has a plurality of sectors separated by a plurality of servo areas, for storing data in the sectors of the tracks; a head for writing data into and reading data from the medium; and a controller for determining whether the head has read out data from a sector on a target track correctly or not in reference to information obtained from servo areas sandwiching the sector and for driving the head so as to retry reading out data from the sector when the controller determines that the head failed to have read out data on the target track, wherein the controller comprises a first counter for counting a count value of thereof at an end of a sector, a second counter for counting a count value of thereof when data is read out with ECC of the data completed, a third counter for holding a count value thereof until servo information is obtained and a fourth counter for holding a count value of the third counter until a verification signal of the next servo information is outputted.

2. The memory device of claim 1 , wherein the controller determines whether or not outputting the data stored in the sector on the basis of the information obtained from the servo areas sandwiching the sector.

3. The memory device of claim 1 , wherein the controller determines that the head has not read data from the sector on the target track when the count value of the fourth counter is not updated.

4. The memory device of claim 1 , wherein the controller comprises a fifth counter for holding the count value of the first counter until servo information is obtained and a sixth counter for holding the lesser value from the second counter and the fifth counter, until the timing of the outputting of the verification signal or the timing of the updating of the second counter.

5. The memory device of claim 4 , wherein the controller comprises a seventh counter for updating a count value of thereof on the basis the count value of the fourth counter and a number of sectors outputted when the count number of the fourth counter is updated or data is outputted.

6. The memory device of claim 5 , wherein the controller controls whether or not outputting data on the basis of the count value of the seventh counter.

7. A method of controlling a memory device having a medium including a plurality of tracks, each of which has a plurality of sectors separated by a plurality of servo areas, for storing data in the sectors of the tracks and a head for writing data into and reading data from the medium, the method comprising: determining whether the head has read out data from a sector on a target track correctly or not in reference to information obtained from servo areas sandwiching the sector; and controlling whether or not outputting data read out by the head on the basis of the determining, wherein the memory device comprises a first counter for counting a count value of thereof at an end of a sector , a second counter for counting a count value of thereof when data is read out with ECC of the data completed, a third counter for holding a count value thereof until servo information is obtained and a fourth counter for holding a count value of the third counter until a verification signal of the next servo information is outputted.

8. The method of claim 7 , further comprising driving the head so as to retry reading out data from the sector when the controller determines that the head failed to have read out data on the target track.

9. The method of claim 7 , wherein the determining determines that the head has not read data from the sector on the target track when the count value of the fourth counter is not updated.

10. The method of claim 7 , wherein the memory device comprises a fifth counter for holding the count value of the first counter until servo information is obtained and a sixth counter for holding the lesser value from the second counter and the fifth counter, until the timing of the outputting of the verification signal or the timing of the updating of the second counter.

11. The method of claim 10 , wherein the memory device further comprises a seventh counter for updating a count value of thereof on the basis the count value of the forth counter and a number of sectors outputted when the count number of the fourth counter is updated or data is outputted.

12. The method of claim 11 , wherein the controlling controls whether or not outputting data on the basis of the count value of the seventh counter.

13. A control apparatus for controlling a head for writing data into and reading data from a medium including a plurality of tracks, each of which has a plurality of sectors separated by a plurality of servo areas, the control apparatus comprising: a determining unit for determining whether the head has read out data from a sector on a target track correctly or not in reference to information obtained from servo areas sandwiching the sector; and a control unit for controlling whether or not outputting data read out by the head on the basis of the determining result of the determining unit, wherein the determining unit comprises a first counter for counting a count value of thereof at an end of a sector, a second counter for counting a count value of thereof when data is read out with ECC of the data completed, a third counter for holding a count value thereof until servo information is obtained and a fourth counter for holding a count value of the third counter until a verification signal of the next servo information is outputted.

14. The control apparatus of claim 13 , wherein the control unit controls not to output data when the determining unit determines that the head fails to have read out data on the target track.